Do any spread betting accounts / platforms allow UK Smaller Companies trades

It depends how small you are looking to go. It may be that you would be able to request a spread on specific companies, but is rare that they will have constant spreads available for very small companies. It may be worth sending an email to multiple companies listing a few specific companies that you intend to trade to see if they would be able to help, I have only used financialspreads.com but they only went as small as FTSE 250 companies I believe