Each police force is different. At one time the Evening Standard reported that the Met was taking up to 15 months to examine computers but I remember seeing adverts for specialist civilian staff specifically to take on that task and I believe that they're now down to around a month or two.
To complicate matters, it seems that some forces refer all computer examinations to specially-trained staff (either 'in house' or external contractors), which can take quite some time, whereas others allow investigating officers (with just a bit of basic training) to make an initial examination and decide whether it's necessary to proceed further.
Two months is a fairly short time period for any matter which might require detailed forensic analysis. A few forces can 'get their act together' within that time but many probably can't.