I was in this exact situation.
If you read through JSP 754, Chapter 4, Section 5 you will find that bounty level is worked out entirely on the number of COE's an Officer/Soldier holds regardless of these being gained under Group A or B service. However there is a footnote regarding UOTC's, it states that COE's earned at UOTC do not count toward bounty level.
In short, if this is your first non UOTC COE, then you should expect a Level 1 Bounty. Also be prepared to get a % of the Level 1 bounty if you have not been on Group A strength for 12 months, this is also in the JSP.
However, you may also get a bigger bounty, unlikely, but I know of OCdt's who transferred and got this. No idea why, but they did. Glasgow told me they shouldn't have got it and the JSP back ups Glasgow.
Hope this clears it up. Finally, if you need to know what JSP XXX states in the future go onto DII (Your admin staff can log you on if you don't have an account) and have a read.
[Edited to add]
As the above poster shows their are always exceptions to this for some reason. But they are simply lucky, the JSP is as I explained above