Aeros, Kemble
Bournemouth Commercial Flight Training
Bristol Flying Centre
Carroll Aviation, Southampton
ETA, Bournemouth
Flightpass, Exeter
Multiflight, Leeds (fairly far North)
PAT, Bournemouth
Probably others I cannot think of, some might no longer offer commercial! I work for one of these, so I will be fair to them all - have put them in alphabetical order, and even included the one I know in the North.
However I will also be fair to you - when pricing ask if VAT and home approach and landing fees are included, and ask for the facilities at the home airport (you will be flying a lot of ILS and NDB approaches so to have them at home will make it cheaper, especially with free home approaches, and if CAA examiners based there then you don't have to go elsewhere for the test). Then you can compare like courses with like pricing.
Go and visit a few, we always like to show people round.