I'm not from the UK either, but we did got marry in a hurry so we could stay together.
We met 3 years ago and started dating dealing with the wonderful long distance we all know about. He doesn't speak French, has been to France once but before he met me and no one in my family met him (well now my brother has).
This was my third visit. It had been almost 8 months since we last saw each other and I was to summarize pretty miserable without him. I have a B2 visa, so I used it to come over. My goal was to find a job and a work visa so I could stay with him.
We had talked about that fact that we wanted to get married someday, but we definitely were not in a hurry for that. I would get so annoyed by our family and friends who kept on asking when we were going to get married. I just didn't feel ready and neither did he. My main fear I think was that marriage would change our relationship.
My first 6 months were getting close to expiring and well I wasn't doing too well with that (even managed to have more fights than we ever did during our trip to Hawaii

), so I asked for an extension.
Getting it accepted took a while, and I was afraid I would have to go back to France within a few days notice, so we talked about our choices and came to the decision to file for the K1 visa. We decided we were not engaged but in the process to be

The extension was accepted and I got a job offer, which was really exciting, but then a few months later they told me they couldn't get a working visa and that was hard to take (it wasn't the first time).
I had enough of not knowing what was next. Neither of us wanting to be apart once again so we decided to go ahead and get married.
We organized it within a month. We didn't want a fancy wedding because what's the point of paying a fortune when most people can't be here anyway? At first we actually wanted to be just the 2 of us and 2 witnesses in front of the magistrate... well it didn't work out that way as soon as we told some of his family and my family that we were getting married. The reactions were diverse:
My parents (who are divorced) were both excited and happy for us, same for my grandmother. They even bought a plane ticket so my brother could be my witness which was totally unexpected. They were relieved to know that we do plan to organize a more formal wedding later on (we're thinking fall 2008) so they would have the time to plan a visit and come.
His mom was well unhappy, mainly because she couldn't come from Hawaii with such a short notice.
My godparent's weren't happy because they were going in France and couldn't attend (it took a while for them to understand that we will have a formal wedding where they can come)
the rest of the family was very excited and his cousin who lives in the area actually organized a party/reception for us, with plenty of friends who joined in and made it feel very special.
So I have no regret on how things worked out. I find that our life since we're married hasn't changed a bit, apart from the fact that now we don't have to worry about me being forced to leave the country again.
I think if it was only for us, we wouldn't even bother to organize a formal wedding, but it matters to both our families so might as well make something special. We plan to exchange personal vows at a semi-religious outdoors ceremony with both families.
In the end it's up to you and how you feel and really how much of a deal you make of being married.
But like most people I asked told me: it's not getting married that changes a relationship, it's having kids.
I think most families do understand that there are specific difficulties you have to deal with when you talk immigration, but they still feel the need to have a 'real wedding' which is why so many people have a courthouse marriage and then a 'family affair wedding.'
I hope you can find a compromise between what you wish and your family expectation, but remember a marriage is only what you make of it.