It's a clever theory Teabreid, but IMO it strains credibility to breaking point.
1. To avoid electronic detection when he leaves Sheffield to return to Bristol, he has to leave his mobile in Sheffield despite the dangerous weather conditions and he has to pay cash at some stage for fuel because even a full tank is probably not going to suffice for the round trip Sheffield-Bristol-Sheffield in a 4x4. This is either a extremely lucky or else proof of pre-meditation.
2. He will take some time to have it out with Joanna, then kill her, then decide what to do, etc, before actually going to dump the body and then doubling back towards Sheffield. He's not going to get back to Sheffield for the second time before 8 am - and that's a stretch. Then he spends the weekend skiing with witnesses - some constitution!
3. He might easily have been seen on his return to Bristol, by a neighbour, or his brother's car might very easily have been seen departing from Sheffield to go back to Bristol, or arriving back in Sheffield early in the morning of 18th December. And he doesn't know in advance that he won't be seen, nor does he know afterwards that he wasn't...
4. He doesn't know when he dumps the body that it will be swiftly covered by snow and remain frozen and undiscovered for several days. Given the place he has chosen to dump it, the antecedent probability is that it will already have been discovered before he gets back on Sunday night. In which case the police will arrive in the flat before he does, so he will never get the chance to spend 4 hours preparing the scene. It is also difficult to see why he needs that long anyway.
5. (Also applies to several other hypotheses but not to all) he has to carry the body through the street to his brother's car where he might easily be spotted.
6. He requires the collusion post factum at least of his brother and his brother's wife and I'm not at all sure why the brother's wife wants to play ball. Not many women are happy to make it easier for men to get away with killing their women.
7. When CJ was in custody, Greg launched a blistering attack on the press for pre-judging his guilt. Remarkable sense of decency if he thought he was the main alternative suspect.
8. If he has quarrelled with Joanna at lunchtime or they've been on the rocks for a while, he certainly has to assume that she has spoken of this to others and that the spotlight will be on him. He also doesn't know that she will be in when he arrives back in Sheffield. Indeed if he really doubts that she is faithful, he won't know that she will be there at all.
9. The main "case" against Greg in fact seems to be that people find it difficult to explain the 4 hours "gap", but it's not hard to explain at all. To anyone used to the varieties of human character and behaviour, there is nothing hard to credit in Gregs account of his discovery of the body or in his subsequent behaviour and comments. Jo is one of those (like me) who dont always answer texts or return calls promptly or at all. At most he is a little surprised at not hearing from her over the weekend. When he gets back on Sunday night, he sees her bag on the table, as he says, but does not yet realise that her keys and mobile are in it. He probably tries to call her, but it doesnt ring audibly because the battery is run down. From the cats behaviour he realises that Jo has been out for quite a while, but he is only bemused, not yet worried. He sorts out his luggage, deals with the cat, makes himself some grub, and having nothing better to while waiting for her, may watch a film or listen to some music or spend an hour or two on line. As time goes by, he becomes more concerned and finally he starts looking round more closely. Already perhaps over three hours have gone by since he got in. It is now that he discovers the keys, phone, purse (US readers note British sense of this word), etc. He becomes quite seriously anxious as he thinks over this, but he is a bit of a ditherer and unsure what to do. He calls his mum OK fairly embarrassing as a reaction, but also understandable and even disarming. Mums sometimes have good advice (pity she didn't tell him to take his hat off while laying the flowers). Shortly afterwards, he calls the police and explains the situation. he also calls Joannas parents, who immediately see the problem and set out. All perfectly credible IMO.
Conclusion, Greg Reardon is innocent.
