Normal for recruiters to ask for your current rate on first call? (Uk)

Just give them the number you want. Don't forget they have only one goal: trying to give you the lowest rate and sell you at the highest rate to the end client to maximize their profit, they'll try everything and won't be afraid to lie.

You may want to read this article http://www.contractoruk.com/agencies/recruitment_agency_tric...

You should not disclose your current rate, and it shouldn't matter what it is currently. What's important is what rate are you aiming at.

You may always try to dodge the question by providing the rate you want/expect.

Note that the law may limit what recruiters are allowed to ask in recruitment process. You need to check regulations in UK.