I don't buy the idea that a bunch of professional British infantrymen - whether light, heavy, airborne or Commando - would, or even should, offer their lives, gladly, in defence of a foreign nation in the same way the gallant and admirable Ukrainian territorials and reservists have been doing. They're fighting an existential war for their national survival, we fight wars of choice - and are significantly (and rightly) more reluctant to take huge casualties, in particular as our resources are both extremely slender and desperately shallow.
The Ukrainian model would be fine if enemy armour were cruising across the South Downs or attempting to outflank our troops at Winchester. Under those circumstances, sure - although where, precisely, we'd lay our hand on the large number of part-trained infantry and irregulars required is an exercise left to the reader to consider - under any others, not so much.
What the war in Ukraine does tell us is that artillery remains king of the battlefield and that fires, supported and informed by ISTAR, are what kill people and make it possible to gain and hold ground.