You're welcome. I guess Halfords or similar would stock them too if you didn't want to buy over the internet. I don't think they would mind you give it a test run in their car park to make sure it's just what you need.
car seat DID fit the car i had at the time of ordering but unfortunately had to change my car. Didn't for a second think seatbelts in cars were different sizes.
Thanks for the helpful comments.