Short answer: there’s no consistent effect of populist right electoral success on any military spending measure (i.e. major parties don’t rush out to boost or cut the military in the same way as they’ve been shown to do on immigration or euroscepticism).

Voter data shows the dilemma is real in voter attitudes. Leave voters are more favorable towards military spending than other voters, BUT are less favorable towards spending on peacekeeping and only as supportive of spending on NATO cooperation as Remain voters.