Without more information this is going to be impossible to answer.
Impossible? I'm not asking for a personalised quote here, just what options are available to UK startups. I probably clouded the water by mentioning my personal situation, but really I'm just interested in what's out there.
Also if your starting a gambling business then payment providers are the least of your concern. You need to be licensed by the UK gaming body - http://www.gamblingcommission.gov.uk.