I managed to sort the problem by looking at the type of CD rom i used to use and I just went on ebay and bought the one nearest in type to it. The amiga recognised it immediately, no hassle.
I used to have a Samsung SCR3230 and I've now got a Samsung SCR 3231 -in fact, I bought 2, in case one fails, i've got a backup.
For the two, I paid £14.98, minus £5.00 (a gift from ebay/paypal) -so all in all, 2 drives for £9.98- i'm happy
Thanks for all your help ppl.