The rules do not stipulate FW separation to be applied to RW - it is just assumed.
The wake vortex is based on weight categories used by ATC L light/ S small /M lower and upper medium /H heavy. Each type including helos have a category allocated to them. Eg R44=L S92=S a320 =M etc. There is no distinction between rotary or FW in the application of the MatsPt1 tables S1 Ch3 P13 also section 9k a bit further down from this link.
https://publicapps.caa.co.uk/docs/33...0117928886.pdf
So a controller shall apply those separations, and they are drummed in under training. Also note separation standards required for parallel runways in said documents. Then ask how does that work with a parallel taxiway and a heli taxiing with skids, eg MD’s Robbo’s,...
A controller has to use those separations, so if you’re at an airfield where rotary has to use the runway for departures and the traffic mix is different weight/wake vortex categories, (and speeds), it can be as frustrating for controllers as it is for the engine drivers...