A few things to be wary of if you shop at Pets @ Home etc, is to stick away from undergravel filters, they are not the most effective filters and work more as a dirt trap than anything else.
Canister filters are the most effective form of filtration for a home aquarium, these are external boxes which hold the filter medium and pump water back into the aquarium. A lot of different manufacturers produce different filters, just buy the one that suits your tank. Eheim are the market leaders but cheaper filters such as Fluval, Aqua-One and Rena etc all do the same job.
Heaters are up to the actual choice you can get at the LFS, just depends what they have.
The tank and hood usually come together anyway, decide on Substrate when you have chosen if you want plants etc and what fish you have, for example Corydoras will need sand as there barbles are very sensitive etc.
Anything else come straight back and ask.
Chris