Hi there and well done for getting started on eating more healthily.
It's a slow old process, but I believe the more slowly you do it, the more sustainable the result will be. If you lose it quickly you are more likely to put it back on, because you can't (or won't want to) maintain those limits to your diet in the long term.
I'm from the UK too and there are loads of UK foods already in the tracker. When you search for a food there are options to search foods entered by other people, or indeed foods you've entered yourself. You can save them as favourites once you've found the right ones, so you don't have to search again every time.
Did you know there's a team for UK sparks? Several actually - the main one is called "UK MAIN - Spark People Team" but there are regional ones too. They would help you with tracking UK foods and all sorts of other questions you might have. Go to the main spark teams page and search for "uk" in the search box to see the various teams.
Don't guess on the tracker!! I made that mistake when I started!
The tracker is a fantastic tool but it is only as useful as it is accurate, so you must weigh everything, at least at the beginning. You wouldn't believe how big I thought 100g of cheddar was to begin with!
Don't give up - you'll get there!