If you have typed the MINUS 5.25 correctly, then you are probably OK.
Look here
http://www.caa.co.uk/docs/49/SRG_MED...InitialVisStds[2189].pdf
and you will see, inter alia :
If you need correction the refractive error (the amount of correction) must not exceed +5.00 dioptres of long sight or -6.00 dioptres of short sight
But the best way by far, instead of speculating on here, is to ask your optician to contact the CAA Med Dept directly with your exact eye details. He will get a prompt, polite and thorough response.