Advice needed for new driver

Hi I’m thinking of going it alone and setting up my own business as an owner driver. I’ve a local company that have jobs going traction only for £525 a day for Derby to Felixstowe and back for 5 days a week. Is this a good rate? If not what should I be looking at asking for?

A good ball park is £400/day fixed costs (driver wages (+ employers NI & pension), lease costs (or depreciation and R&M if owned), vehicle insurance, GIT insurance, employers & public liability insurance, TM, operating centre, o licence costs, road tax, accountant fees, etc, etc) then fuel and tyres on top. So for a 350 mile round trip I would be looking for around £600