I live about 30 min drive from the venue so I might just stay at home now that I will have the added cost of transport and decorators.
As long as your house won't be too busy, I think this is a good idea. You may well sleep a little better in your own bed, and as you said, you now have additional costs to consider. If you have anything in writing from your venue that says about you having a room the night before, I would raise this with your venue - tell them you hadn't budgeted for these additional costs, and can they compensate you in anyway for the inconvenience. They probably won't pay for anything, but they might offer to decorate the venue for you, or chuck in a couple of extra bottles of bubbly!
The prices of most of the accommodation is £30 more on our wedding night than the weekend before and the weekend after our wedding
I would definitely query this. Whenever I've attended a wedding at a hotel, guests have generally been given a discount, not an increase - I mean it's guaranteed money for the venue!
Maybe do a search of your actual wedding dates through booking.com to see if you are actually being ripped off, or if it's just a more expensive weekend - bank holiday maybe?
Either way, I think some convos with your venue are definitely in order, as they are making this experience much more challenging for you!
Good luck! X