BUT, with you being Irish maybe it will be difficult to get a UK visitor visa. The same 'should' work with an Irish visa due to the common travel agreement. Good luck
Ireland isn't part of the schengen zone. So a schengen visa would be of no use. But she can travel to Ireland on a UK visitor visa provided she is in the UK and the entry stamp is still valid
Uk visitor visa is all she needs. This was confirmed by the Irish immigration. Provided she is stamped into the UK and that that stamp is still valid, she can travel from the UK to Ireland. The reason I know this as fact is the while my thai partner was stamped into the UK, we departed Dublin to Thailand and back to Dublin within her 6 month stamp
unless it has changed, the standard visitor visa is valid for 6 months starting from the date you state on the application as to when you intend to travel to the UK. That was what it was around 3 years ago when I successfully applied for my partner's first visa
that's incorrect, there is no requirement to be outside of the UK for 6 months. My partner had a 2 year visa and the majority of those were spent in the UK with a max of 3 months out of the uk