I'm also going to say avoid "The Idiot's Lantern" and "Fear Her" for the same reasons as the other person said. Whenever I re-watch Doctor Who, those are always the episodes I skip. Also, if you're watching on Netflix, "Love and Monsters" has technical issues and the sound doesn't match the video. My niece confirmed that for me, so it's not just my computer going nuts.

In the 4th series, skip The Unicorn and the Wasp, just because it's a boring filler episode and I'd say watch the first five minutes of Midnight and the last 5 minutes since those are the only enjoyable bits to that episode, the rest just drags a bit.