EASA or U.K.?
Either way, no big deal. To get the JAR/EASA back would be training as required based upon when you last used your ASEL, how much time total etc… Should be no big shakes. Usually 3 hours or so would be about right unless you’ve got two left feet!
However, depending upon circumstances, it may be just as easy to convert the AMEL and IR first. So many variables.