Welcome to Autopia gentlemen.
It is possible to spend a lot of money on nice products but it is not necessary. Aside from the basics like shampoo and wash mitts buy the products you need for your car. If you have lots of swirls etc then you will need a fairly strong polish, if the paint is in very good condition, you will only need a mild polish. I guess the best thing to do is identify the problems you wish to fix then decide the other constraints like how much you want to spend and how much protection you want. For example, wax IMO gives the best shine but does not last very long whereas sealants like Zaino will last upto 6 months. Zaino will still give an excellent shine but I think wax looks better. It is all about what you want.
Whatever you do, buy some good quality shampoo, a couple of buckets, as many MF towels as you can and a soft wash mitt.
There are plently of nice things to buy in the UK and the list is growing quickly but if you do need to order from the States, these days it is very easy.
The real difference in shine is not from products but from technique and skill.
There is a healthly contingent of Brits here who are very helpful as is everyone else. So ask away....