Just so you're aware, it's only really 4-5 weeks you'd have to return depending on your a/l entitlement if you are taking the year for mat leave as you accrue leave over mat leave, which for example if worked >5yrs is 32days + 8 bank hols, which is 8 weeks (I'd assume similar if your leave is worked out in hours) but your return to work date is from the end of mat leave and the 3months starts from then. You'd also be entitled to 3months of leave in that time so if you have 32 days then 8 days + bank hols. This means you'd actually only have to return for a few weeks to keep your pay. Hope that makes sense and helps?
That’s the same in the nhs all over the country. I’d defs try and utilise your accrued AL and work for a few weeks to avoid paying back
You’ll only have to return the enhanced portion. SMP is a legality.