If you buy online fron seaworld.com you save $10 on the adult gate price - $68.95 for 1 day. You can print the tickets at home. I think they are still doing the second visit free if you return within 7 days aswell.
All depends on how many days you want in each park, usually 1 day tickets are no cheaper than direct(internet deals sometimes better than gate) but if you want more than 1 day then UK agents could be the best way to go.
For example a 1 day Universal ticket(no hopping) will cost you about £55 but for £80 you can get 14 days unlimited access to both Universal parks with a UK agent. https://www.orlandoattractions.com/tickets/ticket/viewType/49/49
If you go every year also consider Annual passes, for SeaWorld & Busch we buy 2 year 2 park passes, working out at £38/park/year just now incl free parking and good discounts.