Quite a few other clubs use ticketmaster as an outlet but it really depends on the game.
I'd look at Aston Villa, you will be able to get tickets straight from the box office at the moment given their dire state of form. Its a big stadium and wont be selling out for any games in the near future. Its also pretty easy to get to from Bristol as we make the trip every now and then, funnily enough, when watching Bristol City becomes too hard to bear.... we normally get tickets in the Holte End quite easily and they are around £35. Its the home end so obvious rules apply etc etc
Sadly the London clubs are harder to get tickets for, certainly for Arsenal, I know despite the empty seats, the tickets go through various levels of members priority before they go on sale to the general public and invariably, they never get that far. I cant see you ugetting Chelsea or Spurs tickets that easily for the same reasons.
Fulham might be worth a bet but its a smaller ground so they are also quite hard to come by. Ticketmaster is worth a look sometimes as is viagogo or seetickets.
Occasionally, some games are a pay on the day for away fans but this is quite rare in the Premiership, again its worth a look.