Pros
There are two main campuses - in Warrington and in Cumbria. In Cumbria, the lifestyle is everything - the pay is extremely good for the area, the countryside is fabulous and with the majority of the local population having a direct connection to the site there is a huge sense of cameraderie - you'll certainly not get picked out for working 'at that nuclear site'! On the job training is excellent and for self motivators the sky is the limit - sponsorship through second degrees and professional qualifications is easily available and the scope for developing your role is very wide in such a complex and varied organisation. In particular, there is a high proportion of women at all levels.
Cons
Progress on the company mission is achingly slow - government security standards, government purchasing frameworks and endless 'death by committee' progress challenges all conspire to produce huge amounts of financial and working time wastage. The culture can also be hard work for less confident types - to get on you do need to be able to express your opinions (whether right or wrong, controversial or merely loud...)