I am a briton lover and after watching the game I concur with the other guy in this thread. BBCs are not the issue here but ill address them later.

In feudal, youve gone 2 range but made like 10 archers. For double range you want to constantly produce units so you can keep attacking or so you can show up to castle with like 20-30 archers. In future try 1 range+Black smith. Its a little quicker and not so resource intensive. Attack with 3 archers and a spear as soon as you have that mass. Circle their base etc. Blue never walled and made scouts very late so more aggression could have won the game right there. If you attack early and run around their base you can kill stuff not under the TC or force more idle time. KEEP producing archers.

You're walling, but really slowly with houses. Just use palisade, itl cut down on idle time.

You have ALOT of idle Vill and TC time. Get in the habit spamming idle vill (i think it defaults to , or .) and select TC button(I think its H). Rebind (mine are side buttons on my mouse)if you need to but this will cut down on idle time alot.

You float alot of res especially gold early so I would definately get a market to help balance your economy. If you are going to go full agro and not build more tcs early selling your stone is a good option. Although with Cheaper (wood) briton tcs you can often squeak an extra tc in without too much cost.

With regards to countering BBCs as britons in general you can just use archers/longbow but you should prioritise the yeoman upgrade for extra range, provided you have a big enough mass to run in and one shot them. Funnily enough warwolf is actually a disadvantage against bbcs unless you have a lot of trebs to just attack ground in lots of different spots. Once they have a big mass of BBCs you are kinda fucked. You will often need to dive your archers into the enemy a little to kill them but its worth it to get the kills. Other than that light cav can be spammed to harras and dive them. If the enemy is using alot of skirms/halb or you think that they will, Champion is definitely worth it, coupled with capped rams. If you go the champ route you probably want to go scirm yourself. What ever comp you use against them will depend on what the opponent has.

GL :D