You're asking about joining the Royal Engineers in order to work alongside "The Corps" - presumably referring to the Royal Marine Corps. That will go down well in the unlikely event that you do actually get to serve in 24 Cdo Eng Regt (in some capacity other than Sh*thouse cleaner) -
SSgt - "So why did you join The Corps Sapper RA2be?"
Spr RA2be - "I wanted to join The Corps but biffed out in week 27 so joined The Corps where I could serve alongside The Corps and gaze lovingly at them when on exercise with them. I know loads about The Corps and can banter like a sweat with the Airborne lads cos my time in The Corps taught me how to do loads of heaves, chin ups, sit ups and press ups and you don't even have to grip me for mistakenly calling 'the galley' 'the cookhouse', Staff".
Good luck with joining The Corps, or The Royal Armoured Corps or the Royal Corps of Signals or the Royal Regiment of Artillery.