I know of a couple of keepers who got into it later in life, and there very good keepers but they were doing a fair bit of keepering/helping keepers out after doin there day job and runing syndicates and happened to be in the right place at right time when the other keeper left.
While ur tickets/experience could make the difference between u and someone else u still have to equal that other persons skills/experience in either keepering or stalking as that's the skills any future boss should be judging u on
Just as u wouldn't employ a keeper/stalker as a groundy/cutter as they know bugger all about it, so why should someone do the reverse in your situation
Plus the type of job u'd be more likely to get or u see advertised from time to time, will be a small estate as a general dogs body/gardener who also looks after pheasants plus deer, with the focus on pheasants/birds. Possibly even rearing some?
So really u'd need to learn a bit about keepering and get some practical experience. Most smaller estates probably can't justify a FT deer manager so role will either be let out or added onto keepers duty, so keepering experience might be more important than deer (but i'd still be looking to do DSC1+2).
Plus thse smaller estate jobs tend to be single handed so u have no one to show u the ropes and have to know wot ur doing right from the start, even a few K pheasants can cost tens of thousands to release, so not a small outlay
Realistically u'd be better employing an extra person or 2 or expanding to 2 climbing squads if u want to come of the saws in the future, plenty other folk do that.
Or u could look at surveying or more ecological work, so u might still climb but ur not cutting to not lifting/hualing and rigging timber every day, or even jack ur own company in and go as a limbing foreman to a larger company with a view to getting of saws in the future.
My folks told me the same when i left school to be a keeper, ur better off making more money outside of keepering/stalking and then pay for days/syndicates so ur doing ur hobby at ur liesure and ur not sitting in a tied house dependant on the whims of ur boss or how the birds flew the last shoot day (which in some cases can be outwith ur control anyway)
It's not unheard of for keepers to do very well throu the season only for boss to decide he no longer wants a shoot, so ur out a house just like that.