He failed in the pursuit? He advanced 2000 km in 3 months, and by the end of it the battle of medenine happened which demonstrated how changed the british army was under him, while not only Rommel, but also Auchinleck and Wavell, failed to reach the end of their advances with a steady force and not suffer setbacks that reversed their whole advance, while his further advance from Medenine to Sousse and enfidaville in tunisia was the decisive event that made the tunisian campaign end when it did, as seen in the difference of these two maps
https://historicalresources.files.wordpress.com/2008/09/tunisia-situation-22-april-1943.jpg
And no, there was no plan for El alamein formulated. Aunchinleck tried to argue that the plan for Alam el halfa was already formulated. The plan for El Alamein, and the changes done to the strategy as the battle was occuring, were all due to Montgomery. So much "fails" in a 2 week battle the british suffered 12.000 casualties and the germans and italians 70.000, with some 20.000 germans managing to go back to Tunisia simply because they literally stole italian vehicles and etc.
In normandy he did not ignore the US front at all, he had constant meetings with Bradley and Dempsey, and his job was to coordinate them both, and he did that quite well, Montgomery's hand is as much as in Cobra as in Goodwood. (and Goodwood is a singular operation simply because it cant be thought without the main point, that is it was an operation to continue the pressure on the british sector BUT to relieve the infantry divisions and give them some rest, hence why it happened as it did, though note that even in the horrible "disaster" that is goodwood the germans suffered some 3.000 soldiers captured, some 2.000 casualties, while the british overall were 3.000, double standards indeed.)
Oh and, come again, after Goodwood, in mid july, the british switched to the tactics in el alamein? (not to mention that if el alamein is grinding attrition battles its one that causes 7 times as casualties to the opponent?).
Though yes, Montgomery did settle down to the tactics used in El Alamein, because they worked. And he did that from week 2 of the normandy campaign to the end, basically doing limited attacks on the german lines, then preparing these new grounds quickly for the expected german armoured counter attack, planning to diminish the german tank numbers by the use of AT guns, and not have sidi rezegh type battles, but Outpost Snipe all over again.
Market garden is a different thing, rushed indeed, but then it all went down because of the failure of the 82nd to capture the nijmegen bridge quickly, and forcing the guards armoured division to get engaged there instead of just going through. Certainly montgomery could have had a tighter control of the plans, but the context of that period is important. Though, no, market garden is absolutely NOT the single thrust that montgomery was advocating, he was advocating a 40 division thrust in there with 2 army groups, his and bradley's, and not just a few 2nd army divisions and the 3 airborne divisions.
Oh and again, no. 8th army troops, and specially 2nd army troops, loved Montgomery. British and commonwealth troops were well cared for under him, trained, well fed, and etc.
Still, to put things in perspective, montgomery lost 13.000 in market garden. Bradley lost 35.000 in hurtgen forest, Patton 40.000 in Metz and lorraine, and these are at the same period. I mean, it took the americans 100.000 casualties to inflict 70.000 casualties on the germans in the bulge when the germans were in the offensive ffs, Montgomery only needed 13.000 in el alamein, but he is the clown yep. And it is even more funny when saying that the british had to do attrition tactics in normandy, when the british had much LESS casualties than, not only the germans -proportionally too-, but the americans themselves in normandy, and that is while they were fighting the main german opposition, all the tiger tanks and most of the panzer divisions, for the main defensive position the germans prioritized, Caen. So not only did the british suffer the least casualties in normandy, but they also inflicted the most in the germans between june, july and mid august, while after the breakthrough, the british also captured way more germans than the americans.
Imagine if any of the american generals had the record of Montgomery. He would be seen as Napoleon probably.
Though, this is all bloody off topic.