South East is a big place...
...South East US is even bigger.
However, if it is the UK then...
Wycombe Air Centre
Stapleford Flight Centre
Willow Air Southend
BCFT
Bonus at Cranfield
..
..
..
CAA search for the list of approved FTO's and take your pick.
Wycombe did mine - no complaints. But remember, the conversion may not be as simple/easy as the 15 hours the book says it is. Not sure what requirements there would be for SEP to MEP but I'm sure it would be more than the 15 hours.
Cheers
Duchess