Improve our security first
Hitting Russian (or where-ever) targets as revenge or deterrence against future attacks is something that will be done after damage has been done in the UK.
Far better would be to improve security at home: teach UK citizens to be aware of issues and be careful; penalise vendors that are sloppy and do not bother to look for security holes in what they sell, or quickly fix when vulnerabilities are found. This will mean admitting that 'government only encryption back doors' is a fantasy and will make it harder for UK spooks to snoop on us.
Hitting back does not work if foreign ne'er-do-wells are not detected; improving UK security helps a lot here.
It is not easy: most in the UK can't be bothered and think that they don't have to worry - if they screw up it might hurt their employer (so, what ? The still get paid at the end of the month), or if their bank account is hit they will winge until the bank refunds them.
I am far more worried about bad security in Internet of Things (eg baby-cam remote hackable) than I am Huawei exfiltrating packets to China (packets that should be encrypted anyway).