so if i pay £6k in tax paye and my new business makes a loss of £6k i can reclaim the difference?
No, to get the full £6K back your new business would have to suffer a loss of £30,000. You get relief on the loss at the appropriate rate of tax, you don't get the tax back to match the loss pound for pound. And yes, if you employ someone (and that cost is incurred wholly and exclusively for the purposes of the trade) then that will be a deduction from income which will be a factor in calculating a profit or loss.