It's not the fortifications.
It's the air power.
The Czechs best fighter was a biplane. It was the best biplane ever produced, but it was still a biplane.
The fortifications also weren't as tough as Maginot. There's a map
here. Only the red bits were Maginot equivalents (some better). The green were essentially pillboxes at best. Also note the incomplete bits. Yes, the big bunkers were impressive...as the site I linked to says, they were used as practice for Eben Emael. They weren't everywhere.
I've been digging around for the Chiefs of Staff report, but the National Archives aren't cooperating. Found the end of '37 defence expenditure plans, which covers the RAF and how badly outgunned it was compared to the Luftwaffe, and would be up to probably 1941, even with the planned big expansion. CP316(37) "DEFENCE EXPENDITURE IN FUTURE YEARS", if you're at all interested.