To be honest I am not sure you have anything there that can be graded quality wise. But, If you want to get figures graded then they need all their original accessories and need to be as clean and sparkly looking as you can get them - Of the bits above only the last 17 would be worth the effort but as per the photos they are all missing bits. Although hard to tell from the photo's the Yak Face and the Ananaman both look pretty clean, so they may be your better options, but just because you get something graded doesn't mean it will sell either - the collecting community is rather split on graded stuff, a bit like marmite, love it or hate it.
As for the ships/creatures, the Wampa looks pretty clean so anything between £15 and £30 just depends on the day, but most everything else would fall into the beater/spares category. that said, if you can find the missing parts to Jabba's Palace and the Star Destroyer playset and get them cleaned up, they would be the two most valuable items, both go for over 100, if everything is in good order, but all of it in its current state, not so much I afraid.
If you do have a go at cleaning, I recommend a soft toothbrush, warm soapy water (fairliquid) a lot of kitchen roll and take care around the sticker, everything should be done very lightly.