Thanks Brendan, my employer is going to pay my salary in full (maternity benefit + top up my salary) and yes, I'm not sure if starting a business while on maternity can have any impact on my maternity benefit entitlements.
In relation to coming back to work, I want to keep my options open as it's really good job, flexible conditions, well paid, etc so our plan is to set up the business, see how it goes and return to work (either part-time or full-time) after my ML and PL finishes if needed/if I wanted as my husband will look after it & we are planning to take on a few employees then.