All very well, Malcolm, but we are of an age where a bit of sabre rattling used to be nothing unusual. Unfortunately, the UK is now populated by wokeist snowflakes, who would rather learn to speak Russian than pick up a weapon.
Whilst what you say is true, the likelyhood of the UK actually being invaded (thus requiring a snowflake to pick up a weapon) by anyone is as close to zero as possible. Frankly, we're more likely to be invaded by little green men from outer space. Or the French
. If Russia can't sucessfully invade it's (third world military) neighbour (with which it shares a land border), then it stands no chance invading an island thousands of miles from the motherland.
Our military is not what I'd like it to be, but we are still mid table in the premiership, and able to defend ourselves, even if we would (and do) struggle to defend our friends and neighbours. With the US now seen as unreliable, many European countries are re-assessing their own defensive capabilities, and learning off those with the best and most recent (and ongoing) experiance is vital.
Are we? 
As I understand it, we have very little in the way of air defences. No Patriot or THAAD batteries and five of our six T45 Destroyers with air defence capabilities are alongside in Portsmouth undergoing various maintenance/refit programmes so are sitting ducks.
So if Putin or Macron decides to send a few missiles or drones our way, there's probably not much we can do to stop them, and that's if we even see them coming!
I read the other day that all the windfarms in the North Sea cause interference or 'chatter' on ground based radar systems and it might be easy to miss a low flying 'Shahed' type drone for example coming our way.
Although I believe the RAF have recently taken delivery of three planes from Boeing with airborne radar systems? 
Maybe we could spring a couple of WW2 'Ack Ack' guns out of the Imperial War Museum? 
We - the UK - are good at submarines and anti-sub stuff. I would prefer that we had a lot more ASW frigates and AD destroyers but we do have enough (just) to defend the British isles. To get close enough to launch drones an enemy would have to use either ships or subs to launch them. Those ships or subs would be detected, and they would be shadowed and monitored 24/7.
If someone started lobbing missiles at us, then they could expect a Tomahawk type response. Or worst case Trident.
The RAF haven't taken delivery of 3 planes from Boeing yet. The E-7 project is (about) 3 years behind schedule. The first aircraft is supposed to be delivered to it's Scottish base this month, but so far the radar hasn't even been turned on despite there having been about 20 test flights. The second airframe is complete, but it hasn't flown and is sat on the tarmac at Birmingham. The third airframe is still being spannered in the hangar at Birmingham. The whole project is a fuster-cluck. The squadron to operate them is already on it's second CO, and they still haven't even seen an aircraft. We were supposed to be buying an updated version of the aircraft that the Aussies and Turks have been using for 10+ years, on the back of 20+ USAF and 10+ NATO orders. The USAF have cancelled their order, and as a result so have NATO. So we'll end up with a orphan fleet of 3 (possibly 5 eventually) that will be impossible to update/maintain.
Believe it or not, the best radar we currently have for detecting slow & low flying drones is the 1970's one nailed to the navy's Merlin HM2 AEW helicopters. It's an updated version of the one originally fitted to the Gannet and Shakleton aircraft in the 1960's and 70's. That's why some Merlins have been deployed to Akrotiri.