If Edward II dies before 1307 (date of Edward I's death), then he doesn't marry Isabelle of France, daughter of King Philipp IV of France, as he had married her in 1308 OTL. Thus, there will be no Edward III and no Hundred Years' War.
If we applied the English rule of succession, then here is the order of succession at Edward I's death :
1.Thomas of Brotherton, count of Norfolk - A son born to Edward I in 1300 from his second marriage with Margaret of France. He is 7 years old at the time of Edward I's death.
2.Edmond of Woodstock, count of Kent - The second son born to Edward I and Margaret of France. He is 6 years old.
3.Edward I, count of Bar - Son of Eleanor, Edward I's eldest daughter. He is 13 years old, being born in 1294.
4.Eleanor of Bar - Daughter of Eleanor and sister of Edward I of Bar. She is 12.
5.Joan of Bar -Second daughter of Eleanor and sister of Edward I of Bar. She is 12.
6.Gilbert de Clare, 8th Earl of Gloucester - Eldest son of Joan of Acre, second daughter of Edward I. He is currently 16.
7.Thomas de Monthermer - Eldest son from Joan of Acre's second marriage (he is thus Gilbert de Clare's half brother). He is 6 years old.
8.Edward de Monthermer - Second son of Joan of Acre's second marriage. He is 3 years old.
9.Eleanor de Clare - Eldest daughter of Joan of Acre and younger sister of Gilbert de Clare. She is 15.
10.Margaret de Clare - Second daughter of Joan of Acre. She is 14.
11.Elizabeth de Clare - Third daughter of Joan of Acre and her last child from her fist marriage. She is 12.
12.Mary de Monthermer - Eldest daughter of Joan of Acre's second marriage. She is 10 years old and fianced to Duncan Macduff, 8th Earl of Fife.
13.Joan de Monthermer - Second daughter of Joan of Acre's second marriage. She became a nun and is 8 years old when Edward I dies.
14.Margaret - Third daughter of Edward I. She is 32 and married to John II of Brabant.
15.John III, Duke of Brabant - Margaret's son. He is 7.
16.Mary - Fourth daughter of Edward I. She is 28 and a nun.
17.Elizabeth of Rhuddlan - Fifth daughter of Edward I. She is 25 and married to Humphrey de Bohun, 4th Earl of Hereford.
18.John de Bohun, 5th Earl of Hereford - Son of Elizabeth of Rhuddlan. He is only 1 year old.
19.Lady Eleanor de Bohun - Daughter of Elizabeth of Rhuddlan. She is only 3.
20.Eleanor - Only daughter of Edward I and Margaret of France. She is only 1 year old. She died in 1310 OTL.
Considering this, the count of Norfolk will probably be crowned King as he is the first in line. Yet, as he is only 7 at the time of Edward I's death, he will rule under regency, maybe of his mother (whose brother is the King of France Philipp IV).
It also appears that many of the candidates to the throne are minors...