A normal 32A ring with both live wires into the 32A mcb. A 2.5mm T&E cable is screwed into the the 32A ring mcb's terminal. This goes to the garage
A 2.5mm cable taken from a rings MCB counts as a spur off the ring as far as regs are concerned. That means it should only feed one single or double socket or one fused connection unit (FCU). If that is all it feeds then there is no problem otherwise some correction is required.
The best soloution would be to put the garage on it's own breaker. Assuming no thermal insulation is involved in the run you should be able to use a breaker up to 20A.
Another option is to insert a FCU before the first item in the garage so that everything is protected by the fuse in the FCU. This is less preferable though as it limits the total load in the garage to 13A.
All the above assumes an attatched garage and hence relatively short cable runs, with detatched garages volt drop also needs to be taken into account as does the use of a suitable cable type for underground running.