1. Scottish Power are a shower of dicks, switch provider. Octopus seem to be OK
1. Check you hourly usage, can you tie heavy usage to a particular appliance?
1. Get a watt meter and move it from appliance to appliance and see if one is being particularly greedy
1. Keep things off at the wall
Your costs match ours in a 4 bed sandstone terrace with 2 people working from home.