Around here we wire and prune August 15 thru early Sept, no later than Sept 15, but our winters are much more extreme than UK winters. (Chicago-Milwaukee area) Pruning now gives time for dormant buds to activate in preparation to grow in following spring. After August 15 is late enough that pruning does not start a round of new growth that will be too tender to survive winter. Because your UK winters are much more mild than our winters, pruning can happen pretty much anytime autumn through late winter.
Wiring is easiest late summer, thru late winter. Timing is not critical. Late winter wiring is fine as
@Wires_Guy_wires suggests
Repotting is best in late winter, very early spring.
Try not to repot and do heavy pruning in the same year. For a spruce I really like, its older and well on its way, I do no pruning 12 months before repotting, and no pruning 12 months after repotting. I try to go 5 to 10 years between repotting if possible. My media is mostly pumice, with a small amount of fir bark and akadama mixed in.
Younger in training spruces can be repotted more often, but they really don't benefit from root disturbance, so try to plan your repotting so that you don't have to do it often.