Wojciech! Lovely to see you back.

Jon is probably right that one of the thymol methods such as Apiguard is the best in spring. An alternative is drone brood trapping as the colony's expansion gets really underway in about two months. For that you put shallow frames each side of the expanding broodnest and cut off the drone brood formed underneath once it is sealed. However you need to monitor first - you might not have a serious Varroa problem anyway.

The BBKA forum that Jon mentioned is a pale shadow of its former self after those running it alienated most of those posting there. The advice there lately seems (apart from that from Jon, Adam and Ruary) to have been similar to the ineffective methods such as sugar dusting promoted on a 'natural' beekeeping forum. Shook swarming, another tool mentioned there, is hardly used in Scotland and isn't an appropriate method until colonies are a lot stronger than they are now.