Last bit first:
>>> " . . . if I manage to book with Epsom and they go bust . . . , would l get my money back?"
I see no reference here to ABTA membership, or anything similar, so the answer to your question might well be 'No'!
https://www.epsomexplore.co.uk/
(However you can take out an insurance policy to cover you for cancellation for any reason).
91% of reviewers for Grand UK Holidays rate them as 'Excellent' or 'Great' on TrustPilot:
https://uk.trustpilot.com/review/grandukholidays.com
They've got pick-up points across Surrey. (Addlestone, Banstead, Camberley, Caterham, Cobham, Dorking, Epson, Ewell, Farnham, Godalming, Guildford, Horley, Leatherhead, Oxted, Redhill, Reigate, Staines, Walton-on-Thames and Woking).
They have a range of 7-day holidays to Ireland (using overnight stops in Scotland outbound and return).
Although they're also not ABTA members, they offer an insurance policy (through ERGO Insurance) that would protect your money, apart from a £60 excess, if they went bust (as well as covering you for loss of your personal effects and medical cover, etc):
https://www.grandukholidays.com/
(I started typing out some info for Shearings but, having just seen that 50% of TrustPilot reviewers rate them as 'Bad', with a further 9% rating them as 'Poor', I've decided to delete it!)