SWMBO has her own company so not much advantage in stacking her pension. Instead we'll use that in our 50's to make sure we don't pay any (or much) tax on income in our later middle age.
See an accountant. Tomorrow. Or sooner if possible.
Pension contributions from a company are an allowable business expense. They come off the 'profit' before any corporation tax. You can dump up to £40K of profit into her pension plan per year tax free, and carry forward the past 3 years allowance too. So she could extract up to £160K of profit from the company into her pension scheme tax free. There is no cheaper way to extract money from the company, or fund her retirement.
To be fair, I wasn't aware of that, but while ever we aren't making my pension to £40k p.a. I think it would be better to add more to mine. My effective rate is 40%, plus some NI, hers rather less. SWMBO'S Company runs about £45k as PBT and sadly, we need all of it ATM.
I scraped my ACA tax exams, so as soon as we have any spare income, I can assure you I'll be seeking some good advice! 
Something else to consider. You both have a 0% personal allowance of (currently) £11850. If/when you get to 55 and decide you've had enough and want to retire then it is poor planning for one partner to have all the pension income. Take the following scenarios...
1) You have a big pension pot (£1M) and SWIMBO has zero. You take out (say) £40K per year. £11850 is tax free, the rest taxed at 20%, so you'll pay £5630 in tax.
2) You both have similar pension pots (£500K each). You both take out (say) £20K per year. £11850 each is tax free, the rest taxed at 20%, so you pay £1630 tax each, £3260 total.
If you want to retire before state pension age (67..70?) you should try to ensure that SWIMBO's pension pot is big enough to produce a sustained minimum of £11850 per year so that she uses all her tax free personal allowance in retirement. That means the pot size needs to be about £300K if you both want that world cruise at 55. At 67-70 the state pensions kick in so you can then adjust things, and live a life of luxury (and pray comrade Korbyn doesn't get in).