I used to have to make loads of these while living in the UK. Here is my recipe....you will notice that you are using waaaayyy too much butter, syrup and oats which will make it super crunchy or just crumble entirely.
1250g porridge oats
625g brown sugar (not demerrera please)
225g golden syrup
Place all ingredients in a food processor and pulse until fully mixed. DO NOT over mix...make sure the oats keep their texture. Lightly grease your baking tins with butter (not oil or spray as this leaves a bad taste). Spoon in the mixture and spoon spread into the corners making sure it is flat and score your bars.
Place in oven and bake at 180 degrees for 20 minutes (until golden brown). They will be soft when you take them out of the oven so let them sit in the pan for 20 minutes before fiddling with them.
I tend to like to experiment with time and temp as well as additional ingredients. I have found this recipe can endure 160 degrees and 15 mins until just golden and then cool in pan for 30+ mins and it makes a softer product just as yummy. I added a variety of dried fruits and nuts or topped with caramel and chocolate for a unique version of millionaires bar.
Hope this helps and let me know how it goes!!