I work with a lot of clients wanting to marry in the UK but where one half is not a UK national or where both live outside of the country. Whilst it isn't impossible, it does make it harder to have a legal marriage. Whilst it isn't the most fun side of wedding planning, understanding the legalities is pretty important and as it is a question I get asked a lot I thought I'd try and summarise some of the key points as simply as possible. Please please note that rules do change over time so I would advise you to always consult the UK government website to double check the circumstances relevant to your situation. Having said this, hopefully the below will help explain, as simply as possible, your options!
Firstly there are 2 broad types of legal marriage in the UK - religious and civil.
Now, I will start with the civil marriage. A civil marriage can take place in in a registry office or at an approved venue (e.g a stately home or a hotel - check with your venue that they are licensed and check which part of the venue is licensed for wedding ceremonies). If you are not a citizen of Britain or Ireland, if you do not have indefinite leave to remain in the UK or if you do not have settled or pre settled status as part of the EU settlement scheme, you'll need to apply for a VISA to get married. The VISA type will depend on a number of factors and you should check the government website to understand the latest information. You will need to book a ceremony date and time with the venue and the registrars that cover that venue. You will then need to give notice to marry at the registry office which is the local office to where at least one of you lives. This is the key part - you have to have lived in this registration district for at least 7 days prior to giving notice. You will need to bring proof of address to the meeting. This typically means that if you are both living outside of the UK, it is very tricky to have a legal civil marriage in the UK. You must give notice at least 29 days prior to your wedding date and you have 1 year to get married after giving official notice.
A religious marriage can take place in any religious building registered for marriage. However, just like with civil marriage, your chosen church or religious building will have its own legal stipulations as to whether or not you can marry with them. You will need to check these with the minister or person responsible for marrying you. For example, typically, for an Anglican wedding you will need to have some form of connection with the church where you wish to marry in order to marry there. This can include living in the local parish; being a regular attender over a period of some months; having close family connections with the church (e.g. it is the church where you grew up and/or where one of your sets of parents still live). The important thing is to check with the church before you do anything. You will also have to give notice to the local registry office where one or both of you live for getting married in a religious building. This does differ for an Anglican wedding. Typically the notice giving is via the reading of the banns in church. But, again, you should check with the Church, especially if you are not a UK national. In this case you may have to go through the civil process of giving notice.
The complications of the above for couples who live outside of the UK and/or where one or both are not UK national can make it simply impossible to get married over here (or at least too complicated to navigate). If this sounds familiar to you, don't despair! Many of the couples I work with are in a similar situation and there are options. The most common is for my couples to hold the legal ceremony in the country where they are currently living. This happens on an entirely separate date, often in a different month. The beauty of this option is that it leaves you open to then plan the ceremony of your dreams, without restriction. Most of my couples that opt for this route consider their wedding day (not the legal one but the actual celebration) to be their anniversary day. They plan a ceremony with a celebrant. Unlike a civil or religious ceremony, a celebrant in this instance is not bound by any legal "must haves" or "must dos". The ceremony is as you wish it. To all intents and purposes this is your wedding and the guests are non the wiser. It also means that the location is entirely flexible - it does not need to be a venue licensed for marriage. If you always thought you would marry in a church, there are options here too. I have had plenty of couples who do the legal piece prior and then have a church blessing. The word "blessing" could make you think that this service is something less in terms of grandeur and significance - but this is not the case. Again, the service is, to all intents and purposes, in line with a marriage service, albeit with some very subtle shifts in language used.
The blessing/celebrant route is becoming increasingly popular and, in my opinion, these ceremonies are often much more personal, largely down to the flexibility of being able to curate your very own ceremony.
Photography credit to Rebecca Searle