Hi Pando
You could command from £35k - £45k dependant upon experience.
Obviously contract will be more. Although you will be subject to UK IR35 tax code, which means that you will be taxed the same percentage as a permanent employee
If you go to http://www.jobserve.co.uk and search 'oracle dba', you will get a list of about 600 positions currently available in UK, with varying salaries and skill set requirements.
Once you have eliminated all of the impossible,
whatever remains however improbable,
must be true.