your best options will be below the sliding doors. (driver's side or opposite side)
a fellow uk townie owner sent me pics of his townie with intercooler. he had some local aluminium guru weld spigots onto the two parts of the manifold, and then placed a blanking plate between the two parts. Presto, air goes out one pipe and in the other. Fitting a smaller fuel filter cartridge left enough room to get the pipes down.
in my case, it's below the turbo side (below sliding door, passenger side), because below the opposite sliding door has secondary aircon radiator installed.
the toughest part of doing below turbo side will be using the hoses. unless your hose is bendable. you will have hardtime a bit fitting it, finding particular curved hoses. then improvising the intercooler /fan takes time too.
my first plan was putting it in front, below bumper or after the engine radiator, however, it takes longer hose and i worry it will cause to much pressure lose...