Local pub did similar during lockdown, serving freshly pulled Guiness on people’s doorstep 
Like PP tho I recommend a business plan - is there an enterprise scheme is offering business training advice near you?
They can take you through research, business plan, marketing, accounts etc.
I have to say there does seem an explosion of wee trailers offering food/drinks in the regional area I live in, at events like shows, fairs etc and also just parked in lay-bys.
The most important things are a) is there a market for it where you are (eg little or no competition but large ‘footfall’ - ie potential customers) and b) costing it all out accurately so you are realistic re outgoings & pricing.
And look it, if you use the last of your maternity researching business start-up, that’s not wasted effort, many skills are transferable, either to another business idea, or to employers.
I started with one idea, pivoted to another when I saw a gap in the market, and had many, many happy years of work.
Not ‘next year millionaire’ work but dammit it, it rarely even felt like work because I enjoyed it so much and was my own boss.
Give it some thought OP, even if you do nothing further, it is interesting and educational to think about these things and may leave you more open to seeing future opportunities.
(oh and quick disclaimer - I worked well with one of my DSis, but may well have fought like hell with another - family and business can mix but not always!)